Re: [Help-gsl] Problems with siman in c++ class

[Paulo Jabardo]

I've never used these functions but if I understand
correctly your problem, I think you need to declare
your member function static. If it is not declared
static, there is a hidden argument in the method (a
pointer to the object itself, accessible through
"this").


The problem is that you probably want to use instance
variables in your class. To do this you need to pass a
pointer to the object instance that interests you.
I've never used these functions but grasping from the
documentation I guess you are having trouble with the
gsl_siman_Efunc_t type function. This function has an
argument that is a pointer to void (void *xp).

If your class is called MyClass, my suggestion is for
you to create a struct like

struct Efunct_param
{
  MyClass *this;
  // Other parameters needed by the simulation
  ...
};

class MyClass
{
...
   // Function that will be used by gsl_siman_solve
   static double my_fun(void *xp)
   { 
     Efunct_param *par = (MyClass*) xp;
     MyClass *this = par->this;
     // With this you can access instance
variables/methods
    ...
   }

  void function_that_uses_gsl(void)
  {
    Efunc_param pars;
    pars.this = this;
    // set other fields of pars
    gsl_siman_solve(..., my_fun, ...);
  }

  ...
};

I think this might help.

Paulo



--- Ross Williamson <address@hidden>
escreveu:

> Dear all
> 
> I have a c++ class to control and optimize a piece
> of equipment here in
> the lab.  We wish to use simulated annealing package
> from GSL.  We are
> calling the gsl_siman_solve from inside the class
> passing functions that
> are public members of the same class.
> 
> The problem is that we can not get the damn thing to
> compile - we cannot
> simply type the name of the function in instead it
> wants
> &classname::function and that doesn't work either.
> 
> Has anyone got siman running from inside a c++ class
> using functions
> declaired in the class?
> 
> Many thanks
> 
> Ross
> 
> 
> 
> _______________________________________________
> Help-gsl mailing list
> address@hidden
> http://lists.gnu.org/mailman/listinfo/help-gsl
> 


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